Anyhow, I'm just popping in to drum up some interest for a PCB I will have available for folks to DIY with in the not-too-distant future. Here is my post about it:

When I sought out to make a DIY 909 kick drum for my modular, I naturally stumbled across a thread over on Muff's where people were pulling their hair out trying to get some designs others have posted on the 'net working.

It seems to me that there is no easy solution...you can build a 9090, but that's the whole 909. I just want a kick drum module, myself (well, and maybe a clap and snare down the road...)

The general consensus is that none of the PCBs others have made work like they should. Also, none of them have the crucial noise generating circuitry. For some strange reason, they just did not include it.

Anyhow, I'm currently laying out the PCB for a 909 kick clone.

I will be converting component values so it can run from +/-12V and still sound proper. It will also natively support +/-15V like the original.

I will be getting some boards made for myself so was wondering if anyone else would like some as well!

They will be double-sided boards, easy to follow and feature some handy build documentation. I will be providing a Mouser project cart and a BOM to help people get parts easily.

Let me know if you are interested. I'm not taking preorder money but I will keep a running tally so I know how many boards to order, so please let me know if you are interested!

I will be posting sound/video when I prototype.

The board is presently routed and just has to be prototyped, then later, ordered.

There are holes for original 2SA/2SC series transistors if you want to go the rare component route. Otherwise, you can use common BC series transistors.

The board has space for either:

1.) The original Roland CD4006-based noise circuitry
or
2.) a PIC-based 3 component setup that should (in theory) sound the same (tests to come).

...and the regions bounding these parts are clearly labelled.

This is the only diversion from the original circuitry -- the addition of an alternative noise source.

I will have some PICs on hand if folks want one preprogrammed with my noise code programmed into it. I modelled the code to work the same way as the original CD4006 noise generator. White noise is created via a 32bit linear function shift register internally on the PIC -- on the Roland design, it is achieved by two cascaded CD4006s and an XOR gate, instead of in code.

Here is a quick rendering before ground planes and silk-screen is added:

seqSQUARED -- the Analogue Pattern Generator
--> Put yourself on the hexinverter.net mailing list to be notified when in stock!Last edited by HexInverter on Sat Sep 15, 2012 4:49 pm; edited 1 time in total

Hi there, definitely interested in 1 pcb, but this would seal the deal ->"and maybe a clap and snare down the road" hehee.

The video sounds promising

Right on man Glad to have ya on board.

I am also adding an (optional) opamp for buffered output of the noise generator signal -- so, in the future, if I make more of the 909 voices, you don't have to repeat the noise section on each module -- you can then just chain it to the different voices (since almost all of the 909 drums use the signal at some point). The noise section is the only area with some annoying parts in it...the CD4006s are discontinued now. While not hard to find, the NTE replacement at Mouser is $3/pc so it saves ya $6 or so per module if I make more of 'em! _________________hexinverter.net -- Shop DIY projects and modules for modular synthesis

Keep in mind it is running on +/-12V when it should be on 15V. I will need to adjust component values, then it will sound a lot cleaner (less noise once the amplitudes are corrected) as well as the controls working better.

How does one decide on what's a good sub? I know there are some factors (voltage ratings, HFE/beta values, etc) that you can map to rough equivalents, but it seems that most of the general purpose NPN / PNP transistors out there have similar specs?

I just built an 808 kick stripboard from one of the other forum posts here, and it called for BC546 & BC556 per the Eric Archer clone circuit. I didn't have any, so I subbed BC547 and BC557 and I can't really tell the difference between how mine sounds and how samples of the others sound.

I see here you're recommending the 549/559 transistors....why did you pick those?

At some point soon I plan to sub in 2N3904's and see if the sound is any different And I have 546's on order (was supposed to have 556's as well, but, I'll have to take care of that another time )

How does one decide on what's a good sub? I know there are some factors (voltage ratings, HFE/beta values, etc) that you can map to rough equivalents, but it seems that most of the general purpose NPN / PNP transistors out there have similar specs?

I just built an 808 kick stripboard from one of the other forum posts here, and it called for BC546 & BC556 per the Eric Archer clone circuit. I didn't have any, so I subbed BC547 and BC557 and I can't really tell the difference between how mine sounds and how samples of the others sound.

I see here you're recommending the 549/559 transistors....why did you pick those?

At some point soon I plan to sub in 2N3904's and see if the sound is any different And I have 546's on order (was supposed to have 556's as well, but, I'll have to take care of that another time )

The ones used were selected simply for their low noise characteristics That's pretty much it.

You're never going to get the exact same other specifications as the original transistors, so pretty much anything will give good results -- just, maybe not identical, is all!_________________hexinverter.net -- Shop DIY projects and modules for modular synthesis

Usually with PCBs, it's just fine to send over $100 worth of them as lettermail, because lettermail seldom gets lost. It's the small packet stuff that gets lost a lot and I wind up paying out of my pocket for reimbursements for!

Send me a PM and we'll work it out for ya._________________hexinverter.net -- Shop DIY projects and modules for modular synthesis

Usually with PCBs, it's just fine to send over $100 worth of them as lettermail, because lettermail seldom gets lost. It's the small packet stuff that gets lost a lot and I wind up paying out of my pocket for reimbursements for!

Send me a PM and we'll work it out for ya.

I was just after 1x NeinOhNein Kick with transistors, total $88 makes it prohibitively expensive. I don't care for insurance, tracked, or signed for if it's going to triple price of a board. Send it 2nd class basic rate for all I care, even if it takes a month to arrive, I'd rather wait patiently than empty my bank account.

...Or maybe we can get a group buy going in the UK. Anyone in?_________________My tunes available here
(check out the new Electro-Funk LP)

Usually with PCBs, it's just fine to send over $100 worth of them as lettermail, because lettermail seldom gets lost. It's the small packet stuff that gets lost a lot and I wind up paying out of my pocket for reimbursements for!

Send me a PM and we'll work it out for ya.

I was just after 1x NeinOhNein Kick with transistors, total $88 makes it prohibitively expensive. I don't care for insurance, tracked, or signed for if it's going to triple price of a board. Send it 2nd class basic rate for all I care, even if it takes a month to arrive, I'd rather wait patiently than empty my bank account.

...Or maybe we can get a group buy going in the UK. Anyone in?

Hmm...are you sure there was not another shipping option offered? Shipping is more like $8 for that to go in a bubble mailer, as it can go lettermail no problem (and be there in just a couple of weeks, to boot). It shouldn't be your only shipping option...that's express shipping with tracking!

If you're sure there was no other shipping option, it must be that something's wrong in my shipping software that I've not yet noticed. If you wouldn't mind bearing with me I will try and see what's up in my shop's back end._________________hexinverter.net -- Shop DIY projects and modules for modular synthesis

Yeah, if you ever have any troubles with my shop, feel free to email/message me. Usually it's just a shit bug/error in the web software! I am many things, none of which are a good webmaster! LOL_________________hexinverter.net -- Shop DIY projects and modules for modular synthesis

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